A recent study involving over 2,000 preadolescents suggests that exposure to heat and cold during early life may significantly impact the microstructure of white matter in the brain, particularly for children residing in economically disadvantaged neighbourhoods. Published in Nature Climate Change, the research underscores the vulnerability of foetuses and young children to extreme temperatures, highlighting implications for their long-term neurodevelopmental health. Led by the Barcelona Institute for Global Health (ISGlobal) and IDIBELL, in collaboration with Erasmus University Medical Center Rotterdam (ERASMUS MC) and the Centro de Investigación Biomédica en Red (CIBER), the study examines associations between temperature exposure and brain structure, using data from the Generation R Study in Rotterdam.
In the current climate emergency context, the study illuminates the alarming vulnerability of children to temperature fluctuations. Their developing thermoregulatory systems, still maturing during early life stages, make them particularly susceptible to these variations.
Mònica Guxens, a researcher at ISGlobal, Erasmus MC, and CIBERESP, explains, “The developing brain of foetuses and children is highly susceptible to environmental exposures. While preliminary evidence suggests that exposure to heat and cold can affect mental well-being and cognitive performance, studies evaluating structural brain changes due to these exposures are limited.”
The study, led by Guxens, focused on the white matter structure in preadolescent brains to pinpoint vulnerable periods to temperature exposure during early life. The researchers used advanced MRI techniques to assess brain connectivity by analysing water diffusion patterns in white matter. Specifically, they measured mean diffusivity and fractional anisotropy—markers of white matter maturation and integrity.
The findings reveal that exposure to cold during pregnancy and the first year of life and heat from birth to three years old correlated with higher mean diffusivity in preadolescents. This suggests slower maturation of white matter, which is crucial for efficient communication between brain regions. Laura Granés, IDIBELL and ISGlobal researcher and study first author, notes, “White matter fibres facilitate brain communication, and our study indicates that exposure to extreme temperatures may delay this process.”
The study highlights that the most significant changes in brain connectivity parameters occur during early childhood, underscoring the vulnerability of this developmental phase to environmental influences. Carles Soriano, co-author and researcher at IDIBELL, UB, and CIBERSAM, adds, “Our results suggest that temperature exposure during rapid brain development stages may have enduring effects on white matter microstructure.”
Interestingly, no association was found between early life temperature exposure and fractional anisotropy at ages 9-12. The researchers propose that mean diffusivity may provide a more reliable indicator of white matter development than fractional anisotropy.
Further analysis, stratified by socioeconomic status, revealed that children from poorer neighbourhoods exhibited heightened vulnerability to temperature exposure. These children showed similar susceptibility windows to cold and heat but starting earlier, possibly influenced by housing conditions and energy poverty.
Potential mechanisms linking temperature exposure to neurodevelopmental outcomes include disrupted sleep patterns, placental dysfunction, hormonal changes such as increased cortisol production, and inflammatory responses. Guxens underscores, “Our findings highlight the pressing need for robust public health strategies to protect vulnerable communities, particularly amidst ongoing climate challenges.”
The study’s findings underscore the critical impact of early life temperature exposure on brain development, emphasising the urgent need for targeted interventions and policy initiatives to safeguard children’s health in a changing climate landscape.
More information: Laura Granés et al, Early life cold and heat exposure impacts white matter development in children, Nature Climate Change. DOI: 10.1038/s41558-024-02027-w
Journal information: Nature Climate Change Provided by Barcelona Institute for Global Health
